Identifying and distinguishing different types of kidney stones in the human or animal body is very important in deciding on a therapy. Uric acid stones, cystine stones, oxalate stones or hydroxyapatite stones, for example count among the different types of kidney stones. It is chiefly the differentiation between uric acid stones and other types of kidney stones that is of great importance here, since the therapy of uric acid stones differs substantially from those of the other types.
Three different methods have been known to date for differentiating types of kidney stones. In the first method, the uric acid concentration in the blood is determined chemically. A high concentration indicates that a uric acid stone could be present. In the second method, solid constituents are filtered out of the urine. Thus, constituents of kidney stones can sometimes be detected in the urine after bodily movement, for example, through climbing steps, and be suitably investigated. In the third method, a surgical intervention is performed in which the kidney stone is already removed for the purpose of simultaneous diagnosis and therapy. It is possible to classify kidney stones with the aid of conventional computed tomography only with difficulty, since kidney stones do not occur as pure, compact substances. Although, for example, pure calcium oxalate is clearly distinguished from crystallized uric acid in the X-ray attenuation value, the X-ray attenuation values can nevertheless be very similar in reality.